Surface modification to promote golf ball layer adhesion

ABSTRACT

A method for increasing adhesion between golf ball layers comprising the steps of providing a golf ball layer having a first surface; preparing the first surface for treatment; exposing the first layer to a silane; providing a second golf ball layer; and adhering the second layer to the first via the silane. Additionally, a golf ball including an inner component, a molecular monolayer, and at least one cover layer, wherein the inner component and the at least one cover layer have differing surface energies and the cover layer is adhered to inner component with the molecular monolayer.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a non-provisional application claimingpriority to U.S. Provisional Application No. 60/291,275, filed May 16,2001.

FIELD OF THE INVENTION

[0002] This invention relates generally to promoting adhesion betweengolf ball layers. In particular, this invention relates to the use ofsilane coupling agents to promote adhesion between layers of a golf ballcores, intermediate layers, and cover layers.

BACKGROUND

[0003] Conventional golf balls can be divided into two general classes:solid and wound. Solid golf balls include one-piece, two-piece (i.e.,solid core and a cover), and multi-layer (i.e., solid core of one ormore layers and/or a cover of one or more layers) golf balls. Wound golfballs typically include a solid, hollow, or fluid-filled center,surrounded by a tensioned elastomeric material, and a cover. Solid ballshave traditionally been considered longer and more durable than woundballs, but also lack the preferred “feel” provided by the woundconstruction.

[0004] By altering ball construction and composition, manufacturers canvary a wide range of playing characteristics, such as compression,velocity, “feel,” and spin, each of which can be optimized for variousplaying abilities. In particular, a variety of core and cover layer(s)constructions, such as multi-layer balls having dual cover layers and/ordual core layers, have been investigated. These golf ball layers aretypically constructed with a number of polymeric compositions andblends, including polybutadiene rubber, polyurethanes, polyamides, andethylene-based ionomers.

[0005] One problem sometimes encountered by manufacturers whenattempting to construct multi-layered golf balls, however, is improperadhesion between layers. This problem arises when the compositions ofadjacent layers are chemically incompatible, even if only by a smallamount, or when processing conditions required for a particular layerare inconsistent with those required for an adjacent layer. Therefore, aneed exists for development of a better adhesive promoter betweenlayers.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to a method for increasingadhesion between golf ball layers comprising the steps of providing agolf ball layer having a first surface; preparing the first surface fortreatment; exposing the first layer to a silane; providing a second golfball layer; and adhering the second layer to the first via the silane.

[0007] The step of preparing the first surface may include coronadischarge, plasma treatment, washing, drying, rinsing, heating,chilling, a combination thereof, or, additionally, may include the stepsof washing the first surface; exposing the first surface to plasma for apredetermined time; and rotating the first surface. Ideally, theexposure time is less than 10 seconds. To ensure proper exposure tosilane, the first surface should be rotated by at least ¼ turn. The stepof preparing the first surface may also include roughening or gleebargrinding the surface.

[0008] The silane may include a variety of silanes, such as silaneesters; vinyl silanes; methacryloxy silanes; epoxy silanes; sulfursilanes; amino silanes; ureido silanes; or a mixture thereof.Preferably, the silanes include silane esters, octyltriethoxysilane,methyltriethoxylsilane, methyltrimethoxysilane, nonionic silanedispersing agents; vinyl silanes, vinyltriethoxysilane,vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy) silane,vinylmethyldimethoxysilane; methacryloxy silanes,γ-methacryloxypropyltrimethoxysilane; epoxy silanes,β-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane; sulfur silanes,γ-mercaptopropyltrimethoxysilane proprietary polysulfidesilane,bis-(3-[triethoxisily]-propyl)-tetrasulfane; amino silanes,γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solution, modifiedaminoorganosilanes, γ-aminopropyltrimethoxysilane,n-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, modifiedaminoorganosilanes, modified aminosilanes, triaminofinctional silanes,bis-(γ-trimethoxysilylpropyl)amine,n-phenyl-γ-aminopropyltrimethoxysilane, organomodifiedpolydimethylsiloxane, polyazamide silane,n-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; ureido silanes,γ-ureidopropyltrialkoxysilane, γ-ureidopropyltrimethoxysilane;isocyanate silanes, γ-isocyanatopropyltriethoxysilane; or a mixturethereof.

[0009] A preferred class of silanes includes amino silanes, the mostpreferably one being bis-(γ-trimethoxysilylpropyl) amine. Ideally, thesilane is in a solution and is present in an amount of less than about10% by weight. The step of exposing the first surface to a silanetypically includes the step of drying the silane-coated first surface.The second surface, such as an outer cover layer, is typically castabout the first surface and includes saturated or unsaturatedthermoplastic polyurethanes, thermoset polyurethanes, polyureas,epoxies, acrylics, or a mixture thereof.

[0010] The first surface, on the other hand, includes thermoplastics,thermosets, ionic copolymers of ethylene and an unsaturatedmonocarboxylic acid, vinyl resins, polyolefins, polyurethanes,polyureas, polyamides, acrylic resins, polyphenylene oxide resins,thermoplastic polyesters, thermoplastic rubbers, or a mixture thereof.

[0011] The silane may be a silane coupling agent. Additionally, the stepof preparing the first surface comprises generating surface hydroxylgroups prior to the exposing step. The first surface should also have afirst surface energy and the second golf ball layer should have a secondsurface second surface having a second energy different from the first

[0012] The present invention is also directed to a golf ball comprisingan inner component, a molecular monolayer, and at least one cover layer,wherein the inner component and the at least one cover layer havediffering surface energies and the cover layer is adhered to innercomponent with the molecular monolayer.

[0013] The molecular monolayer is preferably a silane including silaneesters; vinyl silanes; methacryloxy silanes; epoxy silanes; sulfursilanes; amino silanes; ureido silanes; or a mixture thereof. Themolecular monolayer, when a silane, includes silane esters,octyltriethoxysilane, methyltriethoxylsilane, methyltrimethoxysilane,nonionic silane dispersing agents; vinyl silanes, vinyltriethoxysilane,vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy) silane,vinylmethyldimethoxysilane; methacryloxy silanes,γ-methacryloxypropyltrimethoxysilane; epoxy silanes,β-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane; sulfur silanes,γ-mercaptopropyltrimethoxysilane proprietary polysulfidesilane,bis-(3-[triethoxisily]-propyl)-tetrasulfane; amino silanes,γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solution, modifiedaminoorganosilanes, γ-aminopropyltrimethoxysilane,n-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, modifiedaminoorganosilanes, modified aminosilanes, triaminofunctional silanes,bis-(γ-trimethoxysilylpropyl)amine,n-phenyl-γ-aminopropyltrimethoxysilane, organomodifiedpolydimethylsiloxane, polyazamide silane,n-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; ureido silanes,γ-ureidopropyltrialkoxysilane, γ-ureidopropyltrimethoxysilane;isocyanate silanes, γ-isocyanatopropyltriethoxysilane; or a mixturethereof. Preferably, the silane comprises an amino silane, ideallybis-(γ-trimethoxysilylpropyl) amine. The silane is in a solution and ispresent in an amount of less than about 10% by weight.

[0014] The inner component is any golf ball component and typicallyincludes a core, solid center, liquid center, intermediate layer, woundlayer, an inner cover layer, or an outer core layer. Ideally, the innercomponent includes a solid center and an inner cover layer.

[0015] The cover layer includes a saturated or unsaturated thermoplasticpolyurethanes, thermoset polyurethanes, polyureas, epoxies, acrylics, ora mixture thereof. In a preferred construction, at least one of theinner component and the cover layer has a thickness of less than about0.05 inches, preferably, between about 0.02 inches and about 0.04inches. In another embodiment, the inner component includes a solidcenter, an outer core layer, and an inner cover layer. The cover layerhas a material hardness of less than about 45 Shore D. Additionally, theinner component may be a casing layer having a material hardness of lessthan about 70 Shore D.

DETAILED DESCRIPTION

[0016] The golf ball of the present invention includes a core and acover surrounding the core. The core and/or the cover may have more thanone layer and an intermediate layer may be disposed between the core andthe cover of the golf ball.

[0017] The golf ball cores of the present invention may comprise any ofa variety of constructions. For example, the core of the golf ball maycomprise a conventional center surrounded by an intermediate or outercore layer disposed between the center and the inner cover layer. Thecore may be a single layer or may comprise a plurality of layers. Theinnermost portion of the core may be solid or it may be a liquid filledsphere. As with the core, the intermediate layer or outer core layer mayalso comprise a plurality of layers. The core may also comprise a solidor liquid filled center around which many yards of a tensionedelastomeric material are wound.

[0018] The materials for solid cores include compositions having a baserubber, a crosslinking agent, a filler, and a co-crosslinking orinitiator agent. The base rubber typically includes natural or syntheticrubbers. A preferred base rubber is 1,4-polybutadiene having acis-structure of at least 40%. Most preferably, the base rubbercomprises high-Mooney-viscosity rubber. If desired, the polybutadienecan also be mixed with other elastomers known in the art such as naturalrubber, polyisoprene rubber and/or styrene-butadiene rubber in order tomodify the properties of the core.

[0019] The crosslinking agent includes a metal salt of an unsaturatedfatty acid such as a zinc salt or a magnesium salt of an unsaturatedfatty acid having 3 to 8 carbon atoms such as acrylic or methacrylicacid. Suitable cross linking agents include one or more metal saltdiacrylates, dimethacrylates and monomethacrylates wherein the metal ismagnesium, calcium, zinc, aluminum, sodium, lithium or nickel. Preferredacrylates include zinc acrylate, zinc diacrylate, zinc methacrylate, andzinc dimethacrylate, and mixtures thereof. The crosslinking agent istypically present in an amount greater than about 10 phr of the polymercomponent, preferably from about 10 to 40 phr of the polymer component,more preferably from about 10 to 30 phr of the polymer component.

[0020] The initiator agent can be any known polymerization initiatorwhich decomposes during the cure cycle. Suitable initiators includeperoxide compounds such as dicumyl peroxide, 1,1-di(t-butylperoxy)3,3,5-trimethyl cyclohexane, a-a bis (t-butylperoxy) diisopropylbenzene,2,5-dimethyl-2,5 di(t-butylperoxy) hexane or di-t-butyl peroxide andmixtures thereof.

[0021] Fillers typically include materials such as tungsten, zinc oxide,barium sulfate, silica, calcium carbonate, zinc carbonate, metals, metaloxides and salts, regrind (recycled core material typically ground toabout 30 mesh particle), high-Mooney-viscosity rubber regrind, and thelike.

[0022] Fillers added to one or more portions of the golf ball typicallyinclude processing aids or compounds to affect rheological and mixingproperties, density-modifying fillers, tear strength, or reinforcementfillers, and the like. The fillers are generally inorganic, and suitablefillers include numerous metals or metal oxides, such as zinc oxide andtin oxide, as well as barium sulfate, zinc sulfate, calcium carbonate,barium carbonate, clay, tungsten, tungsten carbide, an array of silicas,and mixtures thereof. Fillers may also include various foaming agents orblowing agents which may be readily selected by one of ordinary skill inthe art. Fillers may include polymeric, ceramic, metal, and glassmicrospheres may be solid or hollow, and filled or unfilled. Fillers aretypically also added to one or more portions of the golf ball to modifythe density thereof to conform to uniform golf ball standards. Fillersmay also be used to modify the weight of the center or at least oneadditional layer for specialty balls, e.g., a lower weight ball ispreferred for a player having a low swing speed.

[0023] The invention also includes a method to convert the cis-isomer ofthe polybutadiene resilient polymer component to the trans-isomer duringa molding cycle and to form a golf ball. A variety of methods andmaterials have been disclosed in U.S. Pat. No. 6,162,135 and U.S.application Ser. No. 09/461,736, filed Dec. 16, 1999; 09/458,676, filedDec. 10, 1999; and Ser. No. 09/461,421, filed Dec. 16, 1999, each ofwhich are incorporated herein, in their entirety, by reference.

[0024] The materials used in forming either the golf ball center or anyportion of the core, in accordance with the invention, may be combinedto form a mixture by any type of mixing known to one of ordinary skillin the art. Suitable types of mixing include single pass and multi-passmixing. Suitable mixing equipment is well known to those of ordinaryskill in the art, and such equipment may include a Banbury mixer, atwo-roll mill, or a twin screw extruder.

[0025] Conventional mixing speeds for combining polymers are typicallyused. The mixing temperature depends upon the type of polymercomponents, and more importantly, on the type of free-radical initiator.Suitable mixing speeds and temperatures are well-known to those ofordinary skill in the art, or may be readily determined without undueexperimentation.

[0026] The mixture can be subjected to, e.g., a compression or injectionmolding process, to obtain solid spheres for the center or hemisphericalshells for forming an intermediate layer. The temperature and durationof the molding cycle are selected based upon reactivity of the mixture.The molding cycle may have a single step of molding the mixture at asingle temperature for a fixed time duration. The molding cycle may alsoinclude a two-step process, in which the polymer mixture is held in themold at an initial temperature for an initial duration of time, followedby holding at a second, typically higher temperature for a secondduration of time. In a preferred embodiment of the current invention, asingle-step cure cycle is employed. The materials used in forming eitherthe golf ball center or any portion of the core, in accordance with theinvention, may be combined to form a golf ball by an injection moldingprocess, which is also well-known to one of ordinary skill in the art.Although the curing time depends on the various materials selected,those of ordinary skill in the art will be readily able to adjust thecuring time upward or downward based on the particular materials usedand the discussion herein.

[0027] The cover provides the interface between the ball and a club.Properties that are desirable for the cover include good moldability,high abrasion resistance, high tear strength, high resilience, and goodmold release. The cover typically has a thickness to provide sufficientstrength, good performance characteristics, and durability. The coverpreferably has a thickness of less than about 0.1 inches, morepreferably, less than about 0.05 inches, and most preferably, betweenabout 0.02 inches and about 0.04 inches. The invention is particularlydirected towards a multilayer golf ball which comprises a core, an innercover layer, and an outer cover layer. In this embodiment, preferably,at least one of the inner and outer cover layer has a thickness of lessthan about 0.05 inches, more preferably between about 0.02 inches andabout 0.04 inches. Most preferably, the thickness of either layer isabout 0.03 inches.

[0028] When the golf ball of the present invention includes an innercover layer, this layer can include any materials known to those ofordinary skill in the art, including thermoplastic and thermosettingmaterial, but preferably the inner cover can include any suitablematerials, such as ionic copolymers of ethylene and an unsaturatedmonocarboxylic acid which are available under the trademark SURLYN® ofE. I. DuPont de Nemours & Co., of Wilmington, Del., or IOTEK® or ESCOR®of Exxon. These are copolymers or terpolymers of ethylene andmethacrylic acid or acrylic acid partially neutralized with salts ofzinc, sodium, lithium, magnesium, potassium, calcium, manganese, nickelor the like, in which the salts are the reaction product of an olefinhaving from 2 to 8 carbon atoms and an unsaturated monocarboxylic acidhaving 3 to 8 carbon atoms. The carboxylic acid groups of the copolymermay be totally or partially neutralized and might include methacrylic,crotonic, maleic, fumaric or itaconic acid.

[0029] This golf ball can likewise include one or more homopolymeric orcopolymeric inner cover materials, such as:

[0030] (1) Vinyl resins, such as those formed by the polymerization ofvinyl chloride, or by the copolymerization of vinyl chloride with vinylacetate, acrylic esters or vinylidene chloride;

[0031] (2) Polyolefins, such as polyethylene, polypropylene,polybutylene and copolymers such as ethylene methylacrylate, ethyleneethylacrylate, ethylene vinyl acetate, ethylene methacrylic or ethyleneacrylic acid or propylene acrylic acid and copolymers and homopolymersproduced using a single-site catalyst or a metallocene catalyst;

[0032] (3) Polyurethanes, such as those prepared from polyols anddiisocyanates or polyisocyanates and those disclosed in U.S. Pat. No.5,334,673;

[0033] (4) Polyureas, such as those disclosed in U.S. Pat. No.5,484,870;

[0034] (5) Polyamides, such as poly(hexamethylene adipamide) and othersprepared from diamines and dibasic acids, as well as those from aminoacids such as poly(caprolactam), and blends of polyamides with SURLYN®,polyethylene, ethylene copolymers, ethyl-propylene-non-conjugated dieneterpolymer, and the like;

[0035] (6) Acrylic resins and blends of these resins with poly vinylchloride, elastomers, and the like;

[0036] (7) Thermoplastics, such as urethanes; olefinic thermoplasticrubbers, such as blends of polyolefins withethylene-propylene-non-conjugated diene terpolymer; block copolymers ofstyrene and butadiene, isoprene or ethylene-butylene rubber; orcopoly(ether-amide), such as PEBAX®, sold by ELF Atochem ofPhiladelphia, Pa.;

[0037] (8) Polyphenylene oxide resins or blends of polyphenylene oxidewith high impact polystyrene as sold under the trademark NORYL® byGeneral Electric Company of Pittsfield, Mass.;

[0038] (9) Thermoplastic polyesters, such as polyethylene terephthalate,polybutylene terephthalate, polyethylene terephthalate/glycol modifiedand elastomers sold under the trademarks HYTREL® by E.I. DuPont deNemours & Co. of Wilmington, Del., and LOMOD® by General ElectricCompany of Pittsfield, Mass.;

[0039] (10) Blends and alloys, including polycarbonate withacrylonitrile butadiene styrene, polybutylene terephthalate,polyethylene terephthalate, styrene maleic anhydride, polyethylene,elastomers, and the like, and polyvinyl chloride with acrylonitrilebutadiene styrene or ethylene vinyl acetate or other elastomers; and

[0040] (11) Blends of thermoplastic rubbers with polyethylene,propylene, polyacetal, nylon, polyesters, cellulose esters, and thelike.

[0041] Preferably, the inner cover includes polymers, such as ethylene,propylene, butene-1 or hexane-1 based homopolymers or copolymersincluding functional monomers, such as acrylic and methacrylic acid andfully or partially neutralized ionomer resins and their blends, methylacrylate, methyl methacrylate homopolymers and copolymers, imidized,amino group containing polymers, polycarbonate, reinforced polyamides,polyphenylene oxide, high impact polystyrene, polyether ketone,polysulfone, poly(phenylene sulfide), acrylonitrile-butadiene,acrylic-styrene-acrylonitrile, poly(ethylene terephthalate),poly(butylene terephthalate), poly(ethelyne vinyl alcohol),poly(tetrafluoroethylene) and their copolymers including functionalcomonomers, and blends thereof. Suitable cover compositions also includea polyether or polyester thermoplastic urethane, a thermosetpolyurethane, a low modulus ionomer, such as acid-containing ethylenecopolymer ionomers, including E/X/Y terpolymers where E is ethylene, Xis an acrylate or methacrylate-based softening comonomer present inabout 0 to 50 weight percent and Y is acrylic or methacrylic acidpresent in about 5 to 35 weight percent. More preferably, in a low spinrate embodiment designed for maximum distance, the acrylic ormethacrylic acid is present in about 16 to 35 weight percent, making theionomer a high modulus ionomer. In a higher spin embodiment, the innercover layer includes an ionomer where an acid is present in about 10 to15 weight percent and includes a softening comonomer. One skilled in theart would recognize that many of the above materials are suitablemoisture barriers.

[0042] In one embodiment, the outer cover preferably includes apolyurethane composition comprising the reaction product of at least onepolyisocyanate, polyol, and at least one curing Ears agent. Anypolyisocyanate available to one of ordinary skill in the art is suitablefor use according to the invention. Exemplary polyisocyanates include,but are not limited to, 4,4′-diphenylmethane diisocyanate (“MDI”);polymeric MDI; carbodiimide-modified liquid MDI;4,4′-dicyclohexylmethane diisocyanate (“H₁₂MDI”); p-phenylenediisocyanate (“PPDI”); m-phenylene diisocyanate (“MPDI”); toluenediisocyanate (“TDI”); 3,3′-dimethyl-4,4′-biphenylene diisocyanate(“TODI”); isophoronediisocyanate (“IPDI”); hexamethylene diisocyanate(“HDI”); naphthalene diisocyanate (“NDI”); xylene diisocyanate (“XDI”);p-tetramethylxylene diisocyanate (“p-TMXDI”); m-tetramethylxylenediisocyanate (“m-TMXDI”); ethylene diisocyanate;propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyldiisocyanate;1,6-hexamethylene-diisocyanate (“HDI”);dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methylcyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of2,4,4-trimethyl-1,6-hexane diisocyanate (“TMDI”); tetracenediisocyanate; napthalene diisocyanate; anthracene diisocyanate; trimerof IPDI; isocyanurate of toluene diisocyanate; uretdione ofhexamethylene diisocyanate; and mixtures thereof. Polyisocyanates areknown to those of ordinary skill in the art as having more than oneisocyanate group, e.g., di-isocyanate, tri-isocyanate, andtetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI,TDI, or a mixture thereof, and more preferably, the polyisocyanateincludes MDI. It should be understood that, as used herein, the term“MDI” includes 4,4′-diphenylmethane diisocyanate, polymeric MDI,carbodiimide-modified liquid MDI, and mixtures thereof and,additionally, that the diisocyanate employed may be “low free monomer,”understood by one of ordinary skill in the art to have lower levels of“free” monomer isocyanate groups, typically less than about 0.1% freemonomer groups. Examples of “low free monomer” diisocyanates include,but are not limited to Low Free Monomer MDI, Low Free Monomer TDI, andLow Free Monomer PPDI.

[0043] The at least one polyisocyanate should have less than about 14%unreacted NCO groups. Preferably, the at least one polyisocyanate has nogreater than about 7.5% NCO, and more preferably, less than about 7.0%.

[0044] Any polyol available to one of ordinary skill in the art issuitable for use according to the invention. Exemplary polyols include,but are not limited to, polyether polyols, hydroxy-terminatedpolybutadiene (including partially/fully hydrogenated derivatives),polyester polyols, polycaprolactone polyols, and polycarbonate polyols.In one preferred embodiment, the polyol includes polyether polyol.Examples include, but are not limited to, polytetramethylene etherglycol (“PTMEG”), polyethylene propylene glycol, polyoxypropyleneglycol, and mixtures thereof. The hydrocarbon chain can have saturatedor unsaturated bonds and substituted or unsubstituted aromatic andcyclic groups. Preferably, the polyol of the present invention includesPTMEG.

[0045] In another embodiment, polyester polyols are included in thepolyurethane material of the invention. Suitable polyester polyolsinclude, but are not limited to, polyethylene adipate glycol;polybutylene adipate glycol; polyethylene propylene adipate glycol;o-phthalate-1,6-hexanediol; poly(hexamethylene adipate) glycol; andmixtures thereof. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups.

[0046] In another embodiment, polycaprolactone polyols are included inthe materials of the invention. Suitable polycaprolactone polyolsinclude, but are not limited to, 1,6-hexanediol-initiatedpolycaprolactone, diethylene glycol initiated polycaprolactone,trimethylol propane initiated polycaprolactone, neopentyl glycolinitiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone,and mixtures thereof. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups.

[0047] In yet another embodiment, the polycarbonate polyols are includedin the polyurethane material of the invention. Suitable polycarbonatesinclude, but are not limited to, polyphthalate carbonate andpoly(hexamethylene carbonate) glycol. The hydrocarbon chain can havesaturated or unsaturated bonds, or substituted or unsubstituted aromaticand cyclic groups. In one embodiment, the molecular weight of the polyolis from about 200 to about 4000.

[0048] Polyamine curatives are also suitable for use in the polyurethanecomposition of the invention and have been found to improve cut, shear,and impact resistance of the resultant balls. Preferred polyaminecuratives include, but are not limited to,3,5-dimethylthio-2,4-toluenediamine and isomers thereof,3,5-diethyltoluene-2,4-diamine and isomers thereof, such as3,5-diethyltoluene-2,6-diamine;4,4′-bis-(sec-butylamino)-diphenylmethane;1,4-bis-(sec-butylamino)-benzene, 4,4′-methylene-bis-(2-chloroaniline);4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) (“MCDEA”);polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenylmethane; p,p′-methylene dianiline (“MDA”); m-phenylenediamine (“MPDA”);4,4′-methylene-bis-(2-chloroaniline) (“MOCA”);4,4′-methylene-bis-(2,6-diethylaniline) (“MDEA”);4,4′-methylene-bis-(2,3-dichloroaniline) (“MDCA”);4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane;2,2′,3,3′-tetrachloro diarnino diphenylmethane; trimethylene glycoldi-p-aminobenzoate; and mixtures thereof. Preferably, the curing agentof the present invention includes 3,5-dimethylthio-2,4-toluenediamineand isomers thereof, such as ETHACURE® 300, commercially available fromAlbermarle Corporation of Baton Rouge, La. Suitable polyamine curatives,which include both primary and secondary amines, preferably havemolecular weights ranging from about 64 to about 2000.

[0049] At least one of a diol, triol, tetraol, or hydroxy-terminatedcuratives may be added to the aforementioned polyurethane composition.Suitable diol, triol, and tetraol groups include ethylene glycol;diethylene glycol; polyethylene glycol; propylene glycol; polypropyleneglycol; lower molecular weight polytetramethylene ether glycol;1,3-bis(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}benzene;1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;resorcinol-di-(β-hydroxyethyl) ether; hydroquinone-di-(β-hydroxyethyl)ether; and mixtures thereof. Preferred hydroxy-terminated curativesinclude 1,3-bis(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}benzene;1,4-butanediol, and mixtures thereof. Preferably, the hydroxy-terminatedcuratives have molecular weights ranging from about 48 to 2000. Itshould be understood that molecular weight, as used herein, is theabsolute weight average molecular weight and would be understood as suchby one of ordinary skill in the art.

[0050] Both the hydroxy-terminated and amine curatives can include oneor more saturated, unsaturated, aromatic, and cyclic groups.Additionally, the hydroxy-terminated and amine curatives can include oneor more halogen groups. The polyurethane composition can be formed witha blend or mixture of curing agents. If desired, however, thepolyurethane composition may be formed with a single curing agent.

[0051] In a preferred embodiment of the present invention, saturatedpolyurethanes used to form cover layers, preferably the outer coverlayer, and may be selected from among both castable thermoset andthermoplastic polyurethanes.

[0052] In this embodiment, the saturated polyurethanes of the presentinvention are substantially free of aromatic groups or moieties.Saturated polyurethanes suitable for use in the invention are a productof a reaction between at least one polyurethane prepolymer and at leastone saturated curing agent. The polyurethane prepolymer is a productformed by a reaction between at least one saturated polyol and at leastone saturated diisocyanate. As is well known in the art, a catalyst maybe employed to promote the reaction between the curing agent and theisocyanate and polyol.

[0053] Saturated diisocyanates which can be used include, withoutlimitation, ethylene diisocyanate; propylene-1,2-diisocyanate;tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”);2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylenediisocyanate; dodecane-1,12-diisocyanate; dicyclohexylmethanediisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; isophoronediisocyanate (“IPDI”); methyl cyclohexylene diisocyanate; triisocyanateof HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane diisocyanate(“TMDI”). The most preferred saturated diisocyanates are4,4′-dicyclohexylmethane diisocyanate (“HMDI”) and isophoronediisocyanate (“IPDI”).

[0054] Saturated polyols which are appropriate for use in this inventioninclude without limitation polyether polyols such as polytetramethyleneether glycol and poly(oxypropylene) glycol.

[0055] Suitable saturated polyester polyols include polyethylene adipateglycol, polyethylene propylene adipate glycol, polybutylene adipateglycol, polycarbonate polyol and ethylene oxide-capped polyoxypropylenediols. Saturated polycaprolactone polyols which are useful in theinvention include diethylene glycol initiated polycaprolactone,1,4-butanediol initiated polycaprolactone, 1,6-hexanediol initiatedpolycaprolactone; trimethylol propane initiated polycaprolactone,neopentyl glycol initiated polycaprolactone, and polytetramethyleneether glycol-initiated polycaprolactone. The most preferred saturatedpolyols are polytetramethylene ether glycol and PTMEG-initiatedpolycaprolactone.

[0056] Suitable saturated curatives include 1,4-butanediol, ethyleneglycol, diethylene glycol, polytetramethylene ether glycol, propyleneglycol; trimethanolpropane; tetra-(2-hydroxypropyl)-ethylenediamine;isomers and mixtures of isomers of cyclohexyldimethylol, isomers andmixtures of isomers of cyclohexane bis(methylamine);triisopropanolamine, ethylene diamine, diethylene triamine, triethylenetetramine, tetraethylene pentamine, 4,4′-dicyclohexylmethane diamine,2,2,4-trimethyl-1,6-hexanediamine; 2,4,4-trimethyl-1,6-hexanediamine;diethyleneglycol di-(aminopropyl)ether;4,4′-bis-(sec-butylamino)-dicyclohexylmethane;1,2-bis-(sec-butylamino)cyclohexane;1,4-bis-(sec-butylamino)cyclohexane; isophorone diamine, hexamethylenediamine, propylene diamine, 1-methyl-2,4-cyclohexyl diamine,1-methyl-2,6-cyclohexyl diamine, 1,3-diaminopropane, dimethylaminopropylamine, diethylamino propylamine, imido-bis-propylamine, isomersand mixtures of isomers of diaminocyclohexane, monoethanolamine,diethanolamine, triethanolamine, monoisopropanolamine, anddiisopropanolamine. The most preferred saturated curatives are1,4-butanediol, 1,4-cyclohexyldimethylol and4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

[0057] Suitable catalysts include, but are not limited to bismuthcatalyst, oleic acid, triethylenediamine (DABCO®-33LV), di-butyltindilaurate (DABCO®-T12) and acetic acid. The most preferred catalyst isdi-butyltin dilaurate (DABCO®-T12). DABCO® materials are manufactured byAir Products and Chemicals, Inc.

[0058] It is well known in the art that if the saturated polyurethanematerials are to be blended with other thermoplastics, care must betaken in the formulation process so as to produce an end product whichis thermoplastic in nature. Thermoplastic materials may be blended withother thermoplastic materials, but thermosetting materials are difficultif not impossible to blend homogeneously after the thermosettingmaterials are formed. Preferably, the saturated polyurethane comprisesfrom about 1 to about 100%, more preferably from about 10 to about 75%of the cover composition and/or the intermediate layer composition.About 90 to about 10%, more preferably from about 90 to about 25% of thecover and/or the intermediate layer composition is comprised of one ormore other polymers and/or other materials as described below. Suchpolymers include, but are not limited to polyurethane/polyurea ionomers,polyurethanes or polyureas, epoxy resins, polyethylenes, polyamides andpolyesters, polycarbonates and polyacrylin. Unless otherwise statedherein, all percentages are given in percent by weight of the totalcomposition of the golf ball layer in question.

[0059] Polyurethane prepolymers are produced by combining at least onepolyol, such as a polyether, polycaprolactone, polycarbonate or apolyester, and at least one isocyanate. Thermosetting polyurethanes areobtained by curing at least one polyurethane prepolymer with a curingagent selected from a polyamine, triol or tetraol. Thermoplasticpolyurethanes are generally obtained by curing at least one polyurethaneprepolymer with a diol curing agent. The choice of the curatives iscritical because some urethane elastomers that are cured with a dioland/or blends of diols do not produce urethane elastomers with theimpact resistance required in a golf ball cover. Blending the polyaminecuratives with diol cured urethane elastomeric formulations leads to theproduction of thermoset urethanes with improved impact and cutresistance.

[0060] Thermoplastic polyurethanes may be blended with suitablematerials to produce a thermoplastic end product. Examples of suchadditional materials may include ionomers such as the SURLYN®, ESCOR®and IOTEK® copolymers described above.

[0061] Other suitable materials which may be combined with the saturatedpolyurethanes in forming the cover and/or intermediate layer(s)of thegolf balls of the invention include ionic or non-ionic polyurethanes andpolyureas, epoxy resins, polyethylenes, polyamides and polyesters. Forexample, the cover and/or intermediate layer may be formed from a blendof at least one saturated polyurethane and thermoplastic or thermosetionic and non-ionic urethanes and polyurethanes, cationic urethaneionomers and urethane epoxies, ionic and non-ionic polyureas and blendsthereof. Examples of suitable urethane ionomers are disclosed in U.S.Pat. No. 5,692,974 entitled “Golf Ball Covers”, the disclosure of whichis hereby incorporated by reference in its entirety. Other examples ofsuitable polyurethanes are described in U.S. Pat. No. 5,334,673.Examples of appropriate polyureas are discussed in U.S. Pat. No.5,484,870 and examples of suitable polyurethanes cured with epoxy groupcontaining curing agents are disclosed in U.S. Pat. No. 5,908,358, thedisclosures of which are hereby incorporated herein by reference intheir entirety.

[0062] A variety of conventional components can be added to the covercompositions of the present invention. These include, but are notlimited to, white pigment such as TiO₂, ZnO, optical brighteners,surfactants, processing aids, foaming agents, density-controllingfillers, UV stabilizers and light stabilizers. Saturated polyurethanesare resistant to discoloration. However, they are not immune todeterioration in their mechanical properties upon weathering. Additionof UV absorbers and light stabilizers therefore helps to maintain thetensile strength and elongation of the saturated polyurethaneelastomers. Suitable UV absorbers and light stabilizers include TINUVIN®328, TINUVIN® 213, TINUVIN® 765, TINUVIN® 770, TINUVIN® 292, andTINUVIN® 622. The preferred UV absorber is TINUVIN® 328, and thepreferred light stabilizer is TINUVIN 765. TINUVIN® products areavailable from Ciba-Geigy. Dyes, as well as optical brighteners andfluorescent pigments may also be included in the golf ball coversproduced with polymers formed according to the present invention. Suchadditional ingredients may be added in any amounts that will achievetheir desired purpose.

[0063] Any method known to one of ordinary skill in the art may be usedto polyurethanes of the present invention. One commonly employed method,known in the art as a one-shot method, involves concurrent mixing of thepolyisocyanate, polyol, and curing agent. This method results in amixture that is inhomogenous (more random) and affords the manufacturerless control over the molecular structure of the resultant composition.A preferred method of mixing is known as a prepolymer method. In thismethod, the polyisocyanate and the polyol are mixed separately prior toaddition of the curing agent. This method affords a more homogeneousmixture resulting in a more consistent polymer composition. Othermethods suitable for forming the layers of the present invention includereaction injection molding (“RIM”), liquid injection molding (“LIM”),and pre-reacting the components to form an injection moldablethermoplastic polyurethane and then injection molding, all of which areknown to one of ordinary skill in the art.

[0064] Additional components which can be added to the polyurethanecomposition include UV stabilizers and other dyes, as well as opticalbrighteners and fluorescent pigments and dyes. Such additionalingredients may be added in any amounts that will achieve their desiredpurpose.

[0065] It has been found by the present invention that the use of acastable, reactive material, which is applied in a fluid form, makes itpossible to obtain very thin outer cover layers on golf balls.Specifically, it has been found that castable, reactive liquids, whichreact to form a urethane elastomer material, provide desirable very thinouter cover layers.

[0066] The castable, reactive liquid employed to form the urethaneelastomer material can be applied over the core using a variety ofapplication techniques such as spraying, dipping, spin coating, or flowcoating methods which are well known in the art. An example of asuitable coating technique is that which is disclosed in U.S. Pat. No.5,733,428, filed May 2, 1995 entitled “Method And Apparatus For FormingPolyurethane Cover On A Golf Ball,” the disclosure of which is herebyincorporated by reference in its entirety in the present application.

[0067] The outer cover is preferably formed around the inner cover bymixing and introducing the material in the mold halves. It is importantthat the viscosity be measured over time, so that the subsequent stepsof filling each mold half, introducing the core into one half andclosing the mold can be properly timed for accomplishing centering ofthe core cover halves fusion and achieving overall uniformity. Suitableviscosity range of the curing urethane mix for introducing cores intothe mold halves is determined to be approximately between about 2,000 cPand about 30,000 cP, with the preferred range of about 8,000 cP to about15,000 cP.

[0068] To start the cover formation, mixing of the prepolymer andcurative is accomplished in motorized mixer including mixing head byfeeding through lines metered amounts of curative and prepolymer. Toppreheated mold halves are filled and placed in fixture units usingcentering pins moving into holes in each mold. At a later time, a bottommold half or a series of bottom mold halves have similar mixture amountsintroduced into the cavity. After the reacting materials have resided intop mold halves for about 40 to about 80 seconds, a core is lowered at acontrolled speed into the gelling reacting mixture.

[0069] A ball cup holds the ball core through reduced pressure (orpartial vacuum). Upon location of the coated core in the halves of themold after gelling for about 40 to about 80 seconds, the vacuum isreleased allowing core to be released. The mold halves, with core andsolidified cover half thereon, are removed from the centering fixtureunit, inverted and mated with other mold halves which, at an appropriatetime earlier, have had a selected quantity of reacting polyurethaneprepolymer and curing agent introduced therein to commence gelling.

[0070] Similarly, U.S. Pat. No. 5,006,297 to Brown et al. and U.S. Pat.No. 5,334,673 to Wu both also disclose suitable molding techniques whichmay be utilized to apply the castable reactive liquids employed in thepresent invention. Further, U.S. Pat. Nos. 6,180,040 and 6,180,722disclose methods of preparing dual core golf balls. The disclosures ofthese patents are hereby incorporated by reference in their entirety.However, the method of the invention is not limited to the use of thesetechniques.

[0071] Depending on the desired properties, balls prepared according tothe invention can exhibit substantially the same or higher resilience,or coefficient of restitution (“COR”), with a decrease in compression ormodulus, compared to balls of conventional construction. Additionally,balls prepared according to the invention can also exhibit substantiallyhigher resilience, or COR, without an increase in compression, comparedto balls of conventional construction. Another measure of thisresilience is the “loss tangent,” or tan δ, which is obtained whenmeasuring the dynamic stiffness of an object. Loss tangent andterminology relating to such dynamic properties is typically describedaccording to ASTM D4092-90. Thus, a lower loss tangent indicates ahigher resiliency, thereby indicating a higher rebound capacity. Lowloss tangent indicates that most of the energy imparted to a golf ballfrom the club is converted to dynamic energy, i.e., launch velocity andresulting longer distance. The rigidity or compressive stiffness of agolf ball may be measured, for example, by the dynamic stiffness. Ahigher dynamic stiffness indicates a higher compressive stiffness. Toproduce golf balls having a desirable compressive stiffness, the dynamicstiffness of the crosslinked reaction product material should be lessthan about 50,000 N/m at −50° C. Preferably, the dynamic stiffnessshould be between about 10,000 and 40,000 N/m at −50C., more preferably,the dynamic stiffness should be between about 20,000 and 30,000 N/m at−50° C.

[0072] The molding process and composition of golf ball portionstypically results in a gradient of material properties. Methods employedin the prior art generally exploit hardness to quantify these gradients.Hardness is a qualitative measure of static modulus and does notrepresent the modulus of the material at the deformation ratesassociated with golf ball use, i.e., impact by a club. As is well knownto one skilled in the art of polymer science, the time-temperaturesuperposition principle may be used to emulate alternative deformationrates. For golf ball portions including polybutadiene, a 1-Hzoscillation at temperatures between 0° C. and −50° C. are believed to bequalitatively equivalent to golf ball impact rates. Therefore,measurement of loss tangent and dynamic stiffness at 0° C. to −50° C.may be used to accurately anticipate golf ball performance, preferablyat temperatures between about −20° C. and −50° C.

[0073] The resultant golf balls typically have a coefficient ofrestitution of greater than about 0.7, preferably greater than about0.75, and more preferably greater than about 0.78. The golf balls alsotypically have an Atti compression of at least about 40, preferably fromabout 50 to 120, and more preferably from about 60 to 100. The golf ballcured polybutadiene material typically has a hardness of at least about15 Shore A, preferably between about 30 Shore A and 80 Shore D, morepreferably between about 50 Shore A and 60 Shore D.

[0074] The core composition should comprise at least one rubber materialhaving a resilience index of at least about 40. Preferably theresilience index is at least about 50. Polymers that produce resilientgolf balls and, therefore, are suitable for the present invention,include but are not limited to CB23, CB22, commercially available fromof Bayer Corp. of Orange, Tex., BR60, commercially available fromEnichem of Italy, and 1207G, commercially available from Goodyear Corp.of Akron, Ohio.

[0075] Additionally, the unvulcanized rubber, such as polybutadiene, ingolf balls prepared according to the invention typically has a Mooneyviscosity of between about 40 and about 80, more preferably, betweenabout 45 and about 65, and most preferably, between about 45 and about55. Mooney viscosity is typically measured according to ASTM-D1646.

[0076] When golf balls are prepared according to the invention, theytypically will have dimple coverage greater than about 60 percent,preferably greater than about 65 percent, and more preferably greaterthan about 75 percent. The flexural modulus of the cover on the golfballs, as measured by ASTM method D6272-98, Procedure B, is typicallygreater than about 500 psi, and is preferably from about 500 psi to150,000 psi. As discussed herein, the outer cover layer is preferablyformed from a relatively soft polyurethane material. In particular, thematerial of the outer cover layer should have a material hardness, asmeasured by ASTM-D2240, less than about 45 Shore D, preferably less thanabout 40 Shore D, more preferably between about 25 and about 40 Shore D,and most preferably between about 30 and about 40 Shore D. The casingpreferably has a material hardness of less than about 70 Shore D, morepreferably between about 30 and about 70 Shore D, and most preferably,between about 50 and about 65 Shore D.

[0077] In a preferred embodiment, the casing material hardness isbetween about 40 and about 70 Shore D and the outer cover layer materialhardness is less than about 40 Shore D. In a more preferred embodiment,a ratio of the casing material hardness to the outer cover layermaterial hardness is greater than 1.5.

[0078] It should be understood, especially to one of ordinary skill inthe art, that there is a fundamental difference between “materialhardness” and “hardness, as measured directly on a golf ball.” Materialhardness is defined by the procedure set forth in ASTM-D2240 andgenerally involves measuring the hardness of a flat “slab” or “button”formed of the material of which the hardness is to be measured.Hardness, when measured directly on a golf ball (or other sphericalsurface) is a completely different measurement and, therefore, resultsin a different hardness value. This difference results from a number offactors including, but not limited to, ball construction (i.e., coretype, number of core and/or cover layers, etc.), ball (or sphere)diameter, and the material composition of adjacent layers. It shouldalso be understood that the two measurement techniques are not linearlyrelated and, therefore, one hardness value cannot easily be correlatedto the other.

[0079] The core of the present invention has an Atti compression ofbetween about 50 and about 90, more preferably, between about 60 andabout 85, and most preferably, between about 65 and about 85. Theoverall outer diameter (“OD”) of the core is less than about 1.590inches, preferably, no greater than 1.580 inches, more preferablybetween about 1.540 inches and about 1.580 inches, and most preferablybetween about 1.525 inches to about 1.570 inches. The OD of the casingof the golf balls of the present invention is preferably between 1.580inches and about 1.640 inches, more preferably between about 1.590inches to about 1.630 inches, and most preferably between about 1.600inches to about 1.630 inches.

[0080] The present multilayer golf ball can have an overall diameter ofany size. Although the United States Golf Association (“USGA”)specifications limit the minimum size of a competition golf ball to1.680 inches. There is no specification as to the maximum diameter. Golfballs of any size, however, can be used for recreational play. Thepreferred diameter of the present golf balls is from about 1.680 inchesto about 1.800 inches. The more preferred diameter is from about 1.680inches to about 1.760 inches. The most preferred diameter is about 1.680inches to about 1.740 inches.

[0081] The golf balls of the present invention should have a moment ofinertia (“MOI”) of less than about 85 and, preferably, less than about83. The MOI is typically measured on model number MOI-005-104 Moment ofInertia Instrument manufactured by Inertia Dynamics of Collinsville,Conn. The instrument is plugged into a PC for communication via a COMMport and is driven by MOI Instrument Software version #1.2.

[0082] In a preferred embodiment of the present invention, it has beenfound that improved adhesion between golf ball layers, such as betweeninner and outer cover layers, can be achieved when low surface energymaterials, such as ionomers and/or polyurethanes, are treated withsilane coupling agents.

[0083] Silane coupling agents have two different types of reactivegroups:

[0084] X represents an organofunctional group that reacts with organicmaterials, such as synthetic resins, and is typically a vinyl, epoxy,amino, methacryl, acryl, isocyanato, or mercapto group; and ORrepresents the silicon functional group that reacts with inorganicmaterials and is typically a methoxy, ethoxy, or acetoxy groups.

[0085] In the presence of water, coupling agents produce highly reactivesilanols which, in turn, condense to form oligomeric structures. In thismanner, silanes can form durable chemical “bridges” between materials,facilitating bonding between a low energy surface and a polymer matrix.The silane coupling agent forms a covalent bond with both the polymermatrix and the lower energy surface, thereby making a durable, UV andmoisture stable, crosslinked network between the two materials.

[0086] Corona/plasma treatment of the low energy surface createsreaction sites (reactive —OH groups) to which the silicon-functionalgroup can bond. Corona discharge/plasma treatment of golf ball cores andlayers is disclosed in U.S. application Ser. No. 09/389,058, filed Sep.2, 1999, which is incorporated herein, in its entirety, by expressreference thereto. The silane coupling agent is preferably present in aaqueous bath and the corona-treated substrate, preferably a golf ballcore or center (with optional layers), is immersed in the bath. In thismanner, the silane is hydrolized. One of ordinary skill in the art wouldbe aware that a silane may also be hydrolized with ambient moisture. Thesilane then undergoes a condensation reaction with reactive sites on thesubstrate surface allowing the coupling agent to be covalently bound tothe surface, and the surface is removed from the bath. Excess water onthe core surface is allowed to evaporate and the substrate is introducedto a reactive layer component, preferably a polyurethane outer coverlayer. The organofunctional group reacts with the layer precurser tocomplete the “bridge,” improving adhesion between the two layers.

[0087] Suitable silanes include, but are not limited to, silane esters,such as octyltriethoxysilane, methyltriethoxylsilane,methyltrimethoxysilane, and proprietary nonionic silane dispersingagent; vinyl silanes, such as proprietary, vinyltriethoxysilane,vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy) silane,vinylmethyldimethoxysilane; methacryloxy silanes, such asγ-methacryloxypropyltrimethoxysilane; epoxy silanes, such asβ-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane; sulfur silanes, such asgamma-mercaptopropyltrimethoxysilane proprietary polysulfidesilane,bis-(3-[triethoxisily]-propyl)-tetrasulfane; amino silanes, such asγ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solution, modifiedaminoorganosilane, gamma-aminopropyltrimethoxysilane,n-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, modifiedaminoorganosilane (40% in methanol), modified aminosilane (50% inmethanol), triaminofunctional silane,bis-(,γ-trimethoxysilylpropyl)amine,n-phenyl-γ-aminopropyltrimethoxysilane, organomodifiedpolydimethylsiloxane, polyazamide silane (50% in methanol),n-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; ureido silanes,such as gamma-ureidopropyltrialkoxysilane (50% in methanol),γ-ureidopropyltrimethoxysilane; isocyanate silanes, such asγ-isocyanatopropyltriethoxysilane; and mixtures thereof. Preferably, thesilane is an amino silane and more preferably, the amino silane isbis-(γ-trimethoxysilylpropyl) amine.

[0088] The silane treatment may be performed alone or in combinationwith corona discharge and/or plasma treatment. Further, the method ofimproving adhesion may be combined with a plurality of washing and/ordrying steps. Preferably, the surface on which improved adhesion isdesired are washed. The washing step is optionally followed by a rinsingstep but preferably, no rinse step is performed after the first wash.The surface to be treated is then exposed to plasma or corona dischargefor a predetermined time, preferably greater than about 1 sec, morepreferably less than about 10 sec. The surface to be treated can berotated by a predetermined amount to ensure that the maximum surfacearea is properly exposed to the plasma treatment. Preferably the surfaceto be treated is rotated by at least about ¼ turn. The surface mayoptionally undergo surface roughening or gleebar grinding in preparationfor receiving the silane.

[0089] The surface to be treated is exposed to the silane of choice,preferably an amino silane and more preferably,bis-(γ-trimethoxysilylpropyl)amine, commercially available under thetradename Silquest A-1170 from OSi Specialties of Endicott, N.Y. Thesilane may be neat or in solution. Preferably, the silane is present inan amount less than about 10%, more preferably less than about 2%. Thetreated surface is then dried and prepared for final construction into agolf ball. This step may include chilling or preheating a center or acore (and any optional layers thereon), followed by casting of at leastone outer layer.

What is claimed is:
 1. A method for increasing adhesion between golfball layers comprising the steps of: providing a golf ball layer havinga first surface; preparing the first surface for treatment; exposing thefirst layer to a silane; providing a second golf ball layer; andadhering the second layer to the first via the silane.
 2. The method ofclaim 1, wherein the step of preparing the first surface comprisescorona discharge, plasma treatment, washing, drying, rinsing, heating,chilling, or a combination thereof.
 3. The method of claim 1, whereinthe step of preparing the first surface further comprises the steps of:washing the first surface; exposing the first surface to plasma for apredetermined time; and rotating the first surface.
 4. The method ofclaim 3, wherein the time is less than 10 s.
 5. The method of claim 3,wherein the first surface is rotated by at least ¼ turn during theexposing step.
 6. The method of claim 1, wherein the step of preparingthe first surface further comprises the step of surface roughening,gleebar grinding, or a combination thereof.
 7. The method of claim 1,wherein the silane comprises silane esters; vinyl silanes; methacryloxysilanes; epoxy silanes; sulfur silanes; amino silanes; ureido silanes;or a mixture thereof.
 8. The method of claim 1, wherein the silanecomprises silane esters, octyltriethoxysilane, methyltriethoxylsilane,methyltrimethoxysilane, nonionic silane dispersing agents; vinylsilanes, vinyltriethoxysilane, vinyltrimethoxysilane,vinyl-tris-(2-methoxyethoxy) silane, vinylmethyldimethoxysilane;methacryloxy silanes, γ-methacryloxypropyltrimethoxysilane; epoxysilanes, β-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane; sulfur silanes,γ-mercaptopropyltrimethoxysilane proprietary polysulfidesilane,bis-(3-[triethoxisily]-propyl)-tetrasulfane; amino silanes,γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solution, modifiedaminoorganosilanes, γ-aminopropyltrimethoxysilane,n-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, modifiedaminoorganosilanes, modified aminosilanes, triaminofunctional silanes,bis-(γ-trimethoxysilylpropyl)amine,n-phenyl-γ-aminopropyltrimethoxysilane, organomodifiedpolydimethylsiloxane, polyazamide silane,n-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; ureido silanes,γ-ureidopropyltrialkoxysilane, γ-ureidopropyltrimethoxysilane;isocyanate silanes, γ-isocyanatopropyltriethoxysilane; or a mixturethereof.
 9. The method of claim 8, wherein the silane comprises an aminosilane.
 10. The method of claim 9, wherein the amino silane isbis-(γ-trimethoxysilylpropyl) amine.
 11. The method of claim 1, whereinthe silane is in a solution and is present in an amount of less thanabout 10% by weight.
 12. The method of claim 1, wherein the step ofexposing the first surface to a silane further comprises the step ofdrying the first surface.
 13. The method of claim 1, wherein the secondsurface is cast about the first surface.
 14. The method of claim 1,wherein the second golf ball layer comprises saturated or unsaturatedthermoplastic polyurethanes, thermoset polyurethanes, polyureas,epoxies, acrylics, or a mixture thereof.
 15. The method of claim 1,wherein the first golf ball layer comprises thermoplastics, thermosets,ionic copolymers of ethylene and an unsaturated monocarboxylic acid,vinyl resins, polyolefins, polyurethanes, polyureas, polyamides, acrylicresins, polyphenylene oxide resins, thermoplastic polyesters,thermoplastic rubbers, or a mixture thereof.
 16. The method of claim 1,wherein the silane is a silane coupling agent.
 17. The method of claim1, wherein the step of preparing the first surface comprises generatingsurface hydroxyl groups prior to the exposing step.
 18. The method ofclaim 1, wherein the first surface has a first surface energy and thesecond golf ball layer has a second surface second surface having asecond energy different from the first.
 19. A golf ball comprising aninner component, a molecular monolayer, and at least one cover layer,wherein the inner component and the at least one cover layer havediffering surface energies and the cover layer is adhered to innercomponent with the molecular monolayer.
 20. The golf ball of claim 19,wherein the molecular monolayer comprises silane esters; vinyl silanes;methacryloxy silanes; epoxy silanes; sulfur silanes; amino silanes;ureido silanes; or a mixture thereof.
 21. The golf ball of claim 19,wherein the molecular monolayer is a silane comprising silane esters,octyltriethoxysilane, methyltriethoxylsilane, methyltrimethoxysilane,nonionic silane dispersing agents; vinyl silanes, vinyltriethoxysilane,vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy) silane,vinylmethyldimethoxysilane; methacryloxy silanes,γ-methacryloxypropyltrimethoxysilane; epoxy silanes,β-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane; sulfur silanes,γ-mercaptopropyltrimethoxysilane proprietary polysulfidesilane,bis-(3-[triethoxisily]-propyl)-tetrasulfane; amino silanes,γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane,γ-aminopropyltriethoxysilane, aminoalkyl silicone solution, modifiedaminoorganosilanes, γ-aminopropyltrimethoxysilane,n-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, modifiedaminoorganosilanes, modified aminosilanes, triaminofunctional silanes,bis-(γ-trimethoxysilylpropyl)amine,n-phenyl-γ-aminopropyltrimethoxysilane, organomodifiedpolydimethylsiloxane, polyazamide silane,n-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; ureido silanes,γ-ureidopropyltrialkoxysilane (50% in methanol),γ-ureidopropyltrimethoxysilane; isocyanate silanes,γ-isocyanatopropyltriethoxysilane; or a mixture thereof.
 22. The golfball of claim 21, wherein the silane comprises an amino silane.
 23. Thegolf ball of claim 22, wherein the amino silane isbis-(γ-trimethoxysilylpropyl) amine.
 24. The golf ball of claim 19,wherein the silane is in a solution and is present in an amount of lessthan about 10% by weight.
 25. The golf ball of claim 19, wherein theinner component comprises a core, solid center, liquid center,intermediate layer, wound layer, an inner cover layer, or an outer corelayer.
 26. The golf ball of claim 19, wherein the inner componentcomprises a solid center and an inner cover layer.
 27. The golf ball ofclaim 19, wherein the cover layer comprises saturated or unsaturatedthermoplastic polyurethanes, thermoset polyurethanes, polyureas,epoxies, acrylics, or a mixture thereof.
 28. The golf ball of claim 19,wherein at least one of the inner component and the cover layer has athickness of less than about 0.05 inches.
 29. The golf ball of claim 28,wherein the thickness is between about 0.02 inches and about 0.04inches.
 30. The golf ball of claim 19, wherein the inner componentcomprises a solid center, an outer core layer, and an inner cover layer.31. The golf ball of claim 19, wherein the cover layer has a materialhardness of less than about 45 Shore D.
 32. The golf ball of claim 19,wherein the inner component is a casing layer having a material hardnessof less than about 70 Shore D.
 33. A method for increasing adhesionbetween golf ball layers comprising the steps of: providing a firstsurface having a first surface energy; preparing the first surface forbonding; exposing the first surface to a silane; providing a secondsurface having a second surface energy different from the first; andadhering the second surface and the silane.